P0045: Turbocharger/Supercharger Boost Control A Circuit/Open

What does P0045 mean?

"Boost control A" is the electrically driven actuator the engine control module uses to set boost pressure: depending on the engine a pulse-width modulated solenoid or vacuum converter at the wastegate, the control valve of variable turbine vanes, or an electric actuator with position feedback. The letters A and B denote two separate actuators, for example on the low- and high-pressure turbocharger of a two-stage system, not the cylinder banks. This code is set when the control circuit is open: with the driver switched off no load can be measured, or the measured state does not match the command. Without control the actuator usually falls back to its rest position, which on most engines means low boost; depending on the design too much boost is also possible.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

Symptoms

• Check engine light on
• Loss of power or reduced power mode
• Weak acceleration, noticeable turbo lag
• Overboost possible in rare cases

Common causes

• High Connector at the actuator corroded or loose
• High Wire broken or chafed through
• Medium Solenoid coil in the actuator burnt out
• Medium Fuse or ignition supply faulty
• Low Engine control module or separate actuator control unit faulty

Likelihood is a general estimate across vehicles; your make and model may differ.